DBMS SELECT query ~ GNIITHELP

SELECT Query

Select query is used to retrieve data from a tables. It is the most used SQL query. We can retrieve complete tables, or partial by mentioning conditions using WHERE clause.

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Syntax of SELECT Query

SELECT column-name1, column-name2, column-name3, column-nameN from table-name; 

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Example for SELECT Query

Conside the following Student table,

S_id	S_Name	age	address
101	Adam	15	Noida
102	Alex	18	Delhi
103	Abhi	17	Rohtak
104	Ankit	22	Panipat

SELECT s_id, s_name, age from Student.

The above query will fetch information of s_id, s_name and age column from Student table

S_id	S_Name	age
101	Adam	15
102	Alex	18
103	Abhi	17
104	Ankit	22

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Example to Select all Records from Table

A special character asterisk * is used to address all the data(belonging to all columns) in a query. SELECT statement uses * character to retrieve all records from a table.

SELECT * from student; 

The above query will show all the records of Student table, that means it will show complete Student table as result.

S_id	S_Name	age	address
101	Adam	15	Noida
102	Alex	18	Delhi
103	Abhi	17	Rohtak
104	Ankit	22	Panipat

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Example to Select particular Record based on Condition

SELECT * from Student WHERE s_name = 'Abhi';

103

Abhi

17

Rohtak

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Example to Perform Simple Calculations using Select Query

Conside the following Employee table.

eid	Name	age	salary
101	Adam	26	5000
102	Ricky	42	8000
103	Abhi	22	10000
104	Rohan	35	5000

SELECT eid, name, salary+3000  from Employee;

The above command will display a new column in the result, showing 3000 added into existing salaries of the employees.

eid	Name	salary+3000
101	Adam	8000
102	Ricky	11000
103	Abhi	13000
104	Rohan	8000